Researchers at the University of Castilla-La Mancha (Spain), Ecole Nationale des Sciences Appliquees (Agadir, Morocco), and Institut Agronomique et Veterinaire Hassan II (Agadir, Morocco) developed a method for screening paraquat and diquat in olive oil samples. The method involves supercritical fluid extraction (SFE) before continuous flow electrochemical detection. Samples that exhibit total concentrations close to or above a 0.05-g/g threshold limit are then analyzed by liquid chromatography with diode-array detection.